Rotary internal combustion engine

ABSTRACT

A double chamber, four-stage rotary internal combustion engine has a substantially elliptical rotor which is eccentrically mounted on a drive shaft for rotation within a substantially cylindrical casing and is provided with side seals and apex seals which co-operate with the inner surfaces of the casing to define chambers on opposite sides of the rotor. A geared connection between the rotor and the housing ensures that the rotor rotates about the drive shaft so that the volume of each chamber is alternately reduced to a minimum and increased to a maximum, and that the drive shaft rotates at twice the speed of the rotor. Valve gear operably connected to a drive shaft with a speed reduction of 4:1, is effective to control poppet valves or rotary valves for the successive induction of gaseous medium to the chambers within the casing during one revolution of the rotor and successive discharge of gaseous medium from the two chambers during a later revolution of the rotor. The engine may be provided with a sparking plug to initiate combustion, or may operate by compression ignition.

United States Patent [1 1 Knee [ ROTARY INTERNAL COMBUSTION ENGINE [76] Inventor: Gerald John Knee, 43 High St.,

Syresham, Northamptonshire, England 22 Filed: Mar. 31, 1972 21 Appl. 190.; 239,974

[30] Foreign Application Priority Data Apr. 2, 1971 Great Britain 8566/71 [52] US. Cl 123/8.09, 418/54, 418/61, 418/114, 418/138, 418/119 [51] Int. Cl. F02b 53/10 [58] Field of Search 123/809, 8.07, 8.01, 8.13, 123/835, 8.45, 8.49; 418/54, 56, 61, 138

[5 6] References Cited UNlTED STATES PATENTS 1,636,486 7/1927 Planche 418/54 1,340,625 5/1920 Planche 418/54 3,285,189 11/1966 Doyer 4'18/54 1,271,178 7/1918 Lambert.. 123/835 2,231,440 2/1941 Fess 123/849 3,690,791 9/1972 Dieter", 418/69 FOREIGN PATENTS OR APPLICATlONS' 622,734 2/1960 ltaly 123/809 1,188,135 9/1959 France 123/813 Primary Examiner-Clarence R. Gordon Attorney, Agent, or Firm-Woodhams, Blanchard and Flynn [57] ABSTRACT A double chamber, four-stage rotary internal combustion engine has a substantially elliptical rotor which is eccentrically mounted on a drive shaft for rotation within a substantially cylindrical casing and is provided with side seals and apex seals which co-operate with the inner surfaces of the casing to define chambers on opposite sides of the rotor. A geared connection between the rotor'and the housing ensures that the rotor rotates about the drive shaft so that the volume of each chamber is alternately reduced to a minimum and increased to a maximum, and that the drive shaft rotates at twice the speed of the rotor. Valve gear operably connected to a drive shaft with a speed reduction of 4:1, is effective to control poppet valves or rotary valves for the successive induction of gaseous medium to the chambers within the casing during one revolution of the rotor and successive discharge of gaseous medium from the two chambers during a later revolution of the rotor. The engine may be provided with a sparking plug to initiate combustion, or may operate by compression ignition.

5 Claims, 9 Drawing Figures PATENTEDAPR 2 I974 SHEET 2 OF 2 ROTARY INTERNAL COMBUSTION ENGINE The invention relates to a double chamber, fourstage rotary internal combustion engine, and its mode of operation.

In known rotary internal combustion engines, where a rotor rotates in a casing so as to divide the casing into chambers which vary in volume, difficulty arises where the configuration is such that a continuous succession of combustion/expansion stages occurs adjacent one part of the casing wall. Not only does this result in an undesirable temperature gradient around the casing, it also causes sealing problems because of the fact that apex seals provided on the apices of the rotor are periodically caused to slide across this heated part of the casing wall. As a result of the difficulty in lubricating the heated part of the casing wall, the wall and the apex seals are subjected to severe wear during the passage of the apex seals across the heated part of the casing wall. Moreover, the repeated removal of lubricant from the apex seals, as they slide over the heated part of the casing wall, results in further wear in the apex seals and other parts of the casing wall, and makes sealing between the apex seals and the casing wall difficult.

It is an object of the present invention to provide a rotary internal combustion engine in which that part of the casing wall which is subjected to high combustion temperatures is also subjected to the relatively cool inducted gaseous medium during alternate revolutions of the rotor. 1

It is also an object of the invention to provide a rotary internal combustion engine having inlet and exhaust valves which operate cyclically with a period which is four times the period taken for one revolution of the drive shaft. Valve drive gear for actuating the valves may therefore be operably connected to the drive shaft with a speed reduction of 4:1.

It is also an object of the invention to provide a rotary internal combustion engine in which the compression ratio can be controlled, during manufacture, by varying the size of the cavities formed in the radially outer surfaces of the rotor.

According to the invention there is provided a double chamber, four-stage rotary internal combustion engine comprising a substantially elliptical rotor eccentrically mounted for rotation in a casing having a wall defining a substantially cylindrical inner surface, side seals mounted in peripheral edges of sides of the rotor for co-operation with side walls of the casing, sealing means mounted on the apices of the rotor for cooperation with the substantially cylindrical inner surface of the casing to define chambers on opposite sides of the rotor, a drive shaft mounted for rotation in the casing and provided with an eccentric journal which is rotatably disposed within a central bore of the rotor so that on rotation of the rotor the volume of each chamber varies from a maximum to a minimum and back to a maximum, a geared connection between the rotor and the housing to ensure that the drive shaft rotates at twice the speed of the rotor and that the rotor follows a predetermined path around the casing, inlet and exhaust valve means including inlet and exhaust valves mounted in inlet and exhaust ports respectively formed in the wall defining the substantially cylindrical inner surface adjacent the apices of the rotor when the chambers on opposite sides of the rotor are at their maximum and minimum volumes, and valve actuating means connecting the inlet and exhaust valves to the drive shaft through a speed reduction of 4:! so that the inlet port is opened for successive induction to the chambers when the rotor has reduced the volume of one of the chambers to a minimum and closed after two revolutions of the drive shaft, and the exhaust port is opened for successive discharge from the chambers after a further revolution of the drive shaft and closed after a further two revolutions of the drive shaft, the sealing means mounted on the apices of the rotor comprising rockable shoes which are capable of tracking around the substantially cylindrical inner surface and which each carry at least two sealing strips circumferentially spaced by an amount greater than the circumferential extent of the inlet and exhaust ports at the substantially cylindrical inner surface.

The invention also provides a method of inducting, compressing and burning a gaseous medium, and exhausting the products of combustion, in a rotary internal combustion engine comprising a substantially elliptical rotor eccentrically mounted for rotation in a casing having a substantially cylindrical inner surface, a geared connection between the rotor and the housing to ensure that the drive shaft rotates at twice the speed of the rotor and that the rotor follows a predetermined path within the casing, side seals mounted in peripheral edges of sides of the rotor for co-operation with side walls of the casing, and sealing means mounted on the apices of the rotor for co-operation with the substantially cylindrical inner surface of the casing to define chambers on opposite sides of the rotor, which method comprises rotating the rotor within the casing so that the volume of each chamber varies from a maximum to a minimum and back to a maximum during each revolution of the rotor, supplying a gaseous medium to one of the chambers, compressing this gaseous medium, burning the compressed gaseous medium, and exhausting the products of combustion during successive revolutions of the drive shaft, and performing an identical sequence of operations in the other chamber so that each such operation in the sequence is performed first in one chamber and then in the other chamber during successive revolutions of the drive shaft.

It is to be understood that the precise timing of the operation and position of the valves, and the initiation of the combustion may be varied, according to conventional practice, in order to ensure optimum operation.

-is greater than the eccentricity of the ring gear and so it is necessary to separate the fixed pinion from the ring gear. It is then necessary to mount interconnecting planetary gearing on the eccentric journal to mesh with both of the gears.

In a preferred construction of the engine, the inlet valve means comprise a similarly mounted inlet valve, the inlet and exhaust valves being mounted so that they are respectively adjacent the two apices of the rotor when the chambers on opposite sides of the rotor are at their maximum and minimum volumes.

The use of rotary valves in this construction is also advantageous in that, unlike a reciprocating engine, the exhaust valve is not exposed to .the high temperatures or pressures of the power stroke. Although the inlet valve has to tolerate these extremes, it is kept at moderate temperatures by the passage of inducted charge.

As the cycle of operation of the inlet and outlet valves extends over two complete revolutions of the rotor, and over four complete revolutions of the drive shaft, the valve gear is driven by the drive shaft through a speed reduction of 4:1. This reduces the difficulties encountered with high speed valve operation.

Where the substantially cylindrical inner surface of the casing is formed with a recess accommodating the inner end ofa spark plug, or a fuel injector, or recesses formed at the open ends of inlet and exhaust parts formed in the wall providing the substantially cylindrical inner surface, the rockable shoes forming the sealing means mounted on the apices of the rotor are capable of tracking around the substantially cylindrical inner surface. Each of these rockable shoes carries at least two circumferentially spaced sealing strips, the circumferential spacing of the sealing strips being greater than the circumferential extent of any recesses formed in the substantially cylindrical inner surface.

To provide for the greatest possible compression ratios, the radially outer surfaces of the rotor may conform to the substantially cylindrical inner surface of the casing and have cavities which accommodate gaseous medium when the radially outer surfaces of the rotor are closely adjacent the substantially cylindrical inner surface. In this construction, variation in compression ratio may be effected simply by varying the size of the cavities formed in the radially outer surfaces of the rotor.

Two or more double chamber, four-stage rotary internal combustion engines as described above may be interconnected to form a multiple engine. In a preferred form of such a multiple engine, two or more rotors are mounted on a common drive shaft for rotation within separate compartments formed in a common casing.

Three embodiments of rotary internal combustion engines according to the invention, and their mode of operation, are hereinafter described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional side elevation of a first embodiment of the engine;

FIG. 2 is a radial cross section of the engine shown in FIG. 1, taken across the section IIII;

FIGS. 3a to 3e are schematic arrangements of the engine illustrating the cycle of operation; and

FIGS. 40 and 4b are comparative valve diagrams respectively of an engine according to the invention and a twin-cylinder, four-stroke reciprocating internal combustion engine.

As shown in FIGS. 1 and 2, a substantially elliptical rotor 1 is mounted for rotation within a casing 2 having a substantially cylindrical inner surface 3. The rotor l is mounted for rotation with and around an eccentric 4 on a drive shaft 5 journalled in the casing 2. A ring gear 6 mounted on the side of the rotor l co-axially with the eccentric 4 meshes with planetary gearing mounted on the eccentric 4 and schematically represented by planetary gear 7, which in turn meshes with an annular sun gear 8 fixed to the side wall of the casing 2 around the drive shaft 5. The ring gear 6 has twice the number of teeth as the fixed gear 8 so as to ensure that the eccentric carrying the planetary gearing and the drive shaft 5 rotate at twice the speed of rotation of the rotor 1 about the eccentric 4.

This geared connection between the rotor l and the casing 2 enables the rotor l to rotate within the casing 2 so that the chambers formed on opposite sides of the rotor are successively varied from a minimum to a maximum and then back to a minimum.

In the construction illustrated, the curved radially outer faces of the rotor 1 conform closely to the shape of the inner surface 3 of the casing 2, so that cavities 1A have to be formed in these curved faces to provide combustion chambers for the fully compressed inducted charges.

A spark plug 11 is mounted in that part of the casing 2 which together with the rotor l encloses the chambers 9 and 10 when these chambers have their minimum volume, that is to say: when they are constituted solely by the cavities 1A.

Inlet and exhaust ports 12 and 13 are formed in the casing 2 at points adjacent the apices of th rotor 1 when the rotor l is disposed so that the volume of one of the chambers 9 is at a minimum and the volume of the other chamber 10 is at a maximum. Opening and closing of the inlet and outlet ports 12 and 13 is controlled by poppet valves 14. These valves 14 are operated by valve rockers 15 which are actuated by cam driven push rods 16. As shown in FIGS. 1 and 2, a cam shaft 17 carrying cams 17A and 173 which drive the push rods 16 is driven by the drive shaft 5 through a chain and sprocket or gear drive 18 having a speed reduction of 4:] from the drive shaft to the cam shaft.

To prevent leakage of gases between the chambers 9 and 10, the peripheral edges of the sides of the rotor l are provided with side seals 19 for engagement with the side walls of the casing 2, and two apex seals 20 are mounted in spaced positions in a rockable shoe 21 mounted in each apex of the rotor 1. During rotation of the rotor 1, each shoe 21 rocks in its seat in the rotor 1 and allows the shoe 21 to slide around the inner surface 3 of the casing 2 with both of the seals 20 in contact with the surface 3. The spacing between the apex seals 20 is greater than the circumferential extent of the valve ports 12 and 13 and any other recesses or depressions formed in the surface 3 such as the recess around the sparking plug 1 1 or, where the engine operates on a compression ignition cycle, a cavity forming the pre-combustion chamber surrounding the fuel injector.

As shown in FIG. 3a, the rotor 1 has rotated through 45 in a clockwise direction from a position in which a chamber 9 is at minimum volume and the chamber 10 is at maximum volume. Because of the geared connection between the rotor 1 and the casing 2 this rotation of the rotor l is accompanied by a rotation of the drive shaft 5.

During this rotation of the rotor l, the inlet and outlet ports 12 and 13 are open to allow induction of a charge into chamber 9 as chamber 9 increases in volume, and exhaust of the products of combustion in chamber 10 as the volume of chamber 10 decreases. This process takes place during the whole of the first 1 80 rotation of the rotor l and the concurrent 360 rotation' of the eccentric 4 and drive shaft 5.

Duringthe course of the following 180 rotation of the rotor 1,and 360 rotation of the eccentric 4 and drive shaft 5, from the position shown in FIG. 3a, the exhaust port 13 is closed as the leading apex X sweeps past the exhaust port 13 and the volume of chamber is reduced to a minimum. The inlet port 12, however, remains open so that after the trailing apex of the rotor 1 sweeps past the inlet port 12, charge is inducted into the chamber 10 while chamber 10 increases in volume, as shown in FIG. 3b.

The inlet port 12 remains open until, as shown in FIG. 30, the rotor completes its first 360 rotation, the drive shaft 5 having been rotated through 720, and the leading apex X sweeps over the inlet port 12. The inlet port 12 then closes. At this stage, the volumes of the chambers 9 and 10 are respectively at their minimum and maximum values, the compression of the charge in chamber 9 and the induction of charge in chamber 10 have both been completed, and both the inlet and exhaust valves are closed. Combustion is then initiated in chamber 9 by means of the spark plug 11, and the resultant expansion of gases in the chamber 9 causes continued rotation of the rotor 1.

After a further 180 rotation of the rotor l, and 360 rotation of the drive shaft 5, chambers 9 and 10 are at their maximum and minimum volumes, the expansion of the gases in chamber 9 due to combustion has been completed, and the compression of charge in chamber 10 has been completed. At this point, as the apex X is sweeping past the exhaust port 13, the exhaust port 13 is opened and ignition is initiated in the chamber 10 by the spark plug 11, as shown in FIG. 3d.

The resultant expansion of gas in the chamber 10 causes continued rotation of the rotor 1 through a further 180 and 360 rotation of the eccentric 4 and drive shaft 5 and, as the position shown in FIG. 3e during this stage, the products of combustion are discharged from the chamber 9 as the chamber 9 decreases in volume, and the volume of chamber 10 increases until the apex X sweeps over the inlet port 12 which then opens to provide the induction stages illustrated in FIGS. 3a and 3b as the cycle of operation is repeated. As shown in FIG. 3e, the pressure acting on the curved surface of the rotor as a result of combustion in the adjacent chamber has a resultant which acts along a line which is spaced from the axis of the drive shaft 5 by a distance L so as to apply a turning moment to the rotor 1.

Clearly, it is to be understood that the timing of the valve operation and ignition of the charge need not be precisely as described above. Valve overlap and ignition lag or lead, relative to valve operation, may be provided as desired.

In the operation of the engine, as described above, it is clear that the cam shaft rotation is much slower than the drive shaft rotation. As described, one inlet valve and one exhaust valve cycle take place during two rotations of the rotor or four rotations of the drive shaft, this one cycle being effected by a single rotation of the cam shaft 17. A comparison of the duration of the valve cycles of the engine with the duration of the valve cycles of a comparable twin-cylinder, four-stroke reciprocating internal combustion engine is illustrated in FIGS. 40 and 4b.

In these figures, rotation of the rotor is shown on the x axis and the extent of valve opening is shown on the y axis. As shown by the inlet and exhaust valve curves A and B in FIG. 4a, the inlet port is open during alternate revolutions of the rotor, and the exhaust port opens after the inlet port has been closed for a period in which the'rotor completes one half of a revolution and remains open during the first half of the period in which the inlet valve is open. This opening of the inlet port allows induction successively to the chambers on opposite sides of the rotor. In the same way, during half of the period in which the exhaust valve is open, the products of combustion are exhausted from the chamber on one side of the rotor, whereas during the second half of the period in which the exhaust valve is open, the products of combustion are discharged from the chamber on theother side of the rotor.

As the area under each valve curve represents the product of the extent of valve opening and time, this product is a measure of the volume of fluid flow to or from the engine.

The valve diagram for a twin-cylinder, four-stroke reciprocating internal combustion engine is shown in FIG. 4b where curves E and F respectively represent the operation of the inlet valves of the first and second cylinders, the curves G and E respectively represent the operation of the exhaust valves of these two cylinders.

Thus, if the areas under the valve curves E and F in FIG. 4b are subtracted from the area under curve A in FIG. 4a, and the areas under curves G and E in FIG. 4b are subtracted from the area under the curve B in FIG. 4a, the remaining areas C and D shown in FIG. 4a represent, at least in general terms, an increase in volumetric efficiency of the double chamber, four-stage rotary internal combustion engine over the twin cylinder, four stroke reciprocating engine.

Although, in the description above, reference has been made to the use of a spark plug, it is to be understood that this form of construction is equally suited to compression ignition engines where the spark plug is replaced with a fuel injector nozzle.

I claim:

1. A double chamber, four-stage rotary internal combustion engine comprising a substantially elliptical rotor eccentrically mounted for rotation in a casing having a wall defining a substantially cylindrical inner surface, side seals mounted in peripheral edges of sides of the rotor for cooperation with said walls of the casing, sealing means mounted on the apices of the rotor for cooperation with the substantially cylindrical inner surface of the casing to define chambers on opposite sides of the rotor, a drive shaft mounted for rotation in the casing and provided with an eccentric journal which is rotatably disposed within a central bore formed within the rotor so that on rotation of the rotor the volume of each chamber varies from a maximum to a minimum and back to a maximum, and a geared connection between the rotor and the housing to ensure that the drive shaft rotates at twice the speed of the rotor and that the rotor follows a predetermined path around the casing, inlet and exhaust valve means including inlet and exhaust valves mounted in inlet and exhaust ports respectively formed in the wall defining the substantially cylindrical inner surface adjacent the apices of the rotor when the chambers on opposite sides of the rotor are at their maximum and minimum volumes, and valve actuating means connecting the inlet and exhaust valves to the drive shaft through a speed reduction of 4:1 so that the inlet port is opened for successive induction to the chambers when the rotor has reduced the volume of one of the chambers to a minimum and closed after two revolutions of the drive shaft, and the exhaust port is opened for successive discharge from the chambers after a further revolution of the drive shaft and closed after a further two revolutions of the drive shaft, the sealing means mounted on the apices of the rotor comprising rockable shoes which are capable of tracking around the substantially cylindrical inner surface and which each carry at least two sealing strips circumferentially spaced by an amount greater than the circumferential extent of th inlet and exhaust ports at the substantially cylindrical inner surface.

2. A double chamber, four-stage rotary internal combustion engine according to claim 1, in which the radially outer surfaces of the rotor conform to the substantially cylindrical inner surface of the casing and have cavities which accommodate gaseous medium when the radially outer surfaces of the rotor are closely adjacent the substantially cylindrical inner surface.

3. A double chamber, four-stage rotary internal combustion engine according to claim 1, in which a sparking plug is provided in a recess formed in the substantially cylindrical inner wall for initiating combustion, the circumferential extent of the cavity being less than the circumferential spacing of the sealing strips of each rockable shoe.

4. A double chamber, four-stage rotary internal combustion engine according to claim 1, in which there is provided a fuel injector mounted in a recess formed in the substantially cylindrical inner surface of the casing, the circumferential extent of the recess being less than the circumferential spacing of the sealing strips of each rockable shoe.

5. A multiple engine comprising at least two double chamber, four-stage rotary internal combustion engines according to claim 1, in which the drive shafts are connected together and the casings form part of a multiple casing. 

1. A double chamber, four-stage rotary internal combustion engine comprising a substantially elliptical rotor eccentrically mounted for rotation in a casing having a wall defining a substantially cylindrical inner surface, side seals mounted in peripheral edges of sides of the rotor for cooperation with said walls of the casing, sealing means mounted on the apices of the rotor for cooperation with the substantially cylindrical inner surface of the casing to define chambers on opposite sides of the rotor, a drive shaft mounted for rotation in the casing and provided with an eccentric journal which is rotatably disposed within a central bore formed within the rotor so that on rotation of the rotor the volume of each chamber varies from a maximum to a minimum and back to a maximum, and a geared connection between the rotor and the housing to ensure that the drive shaft rotates at twice the speed of the rotor and that the rotor follows a predetermined path around the casing, inlet and exhaust valve means including inlet and exhaust valves mounted in inlet and exhaust ports respectively formed in the wall defining the substantially cylindrical inner surface adjacent the apices of the rotor when the chambers on opposite sides of the rotor are at their maximum and minimum volumes, and valve actuating means connecting the inlet and exhaust valves to the drive shaft through a speed reduction of 4:1 so that the inlet port is opened for successive induction to the chambers when the rotor has reduced the volume of one of the chambers to a minimum and closed after two revolutions of the drive shaft, and the exhaust port is opened for successive discharge from the chambers after a further revolution of the drive shaft and closed after a further two revolutions of the drive shaft, the sealing means mounted on the apices of the rotor comprising rockable shoes which are capable of tracking around the substantially cylindrical inner surface and which each carry at least two sealing strips circumferentially spaced by an amount greater than the circumferential extent of th inlet and exhaust ports at the substantially cylindrical inner surface.
 2. A double chamber, four-stage rotary internal combustion engine according to claim 1, in which the radially outer surfaces of the rotor conform to the substantially cylindrical inner surface of the casing and have cavities which accommodate gaseous medium when the radially outer surfaces of the rotor are closely adjacent the substantially cylindrical inner surface.
 3. A double chamber, four-stage rotary internal combustion engine according to claim 1, in which a sparking plug is provided in a recess formed in the substantially cylindrical inner wall for initiating combustion, the circumferential extent of the cavity being less than the circumferential spacing of the sealing strips of each rockable shoe.
 4. A double chamber, four-stage rotary internal combustion engine according to claim 1, in which there is provided a fuel injector mounted in a recess formed in the substantially cylindrical inner surface of the casing, the circumferential extent of the recess being less than the circumferential spacing of the sealing strips of each rockable shoe.
 5. A multiple engine comprising at least two double chamber, four-stage rotary internal combustion engines according to claim 1, in which the drive shafts are connected together and the casings form part of a multiple casing. 